Method and apparatus for completing a circuit switched service call in an internet protocol network

ABSTRACT

A method and an apparatus for processing a session request in an Internet Protocol network are disclosed. For example, the method receives a session request, and queries an tElephone NUmbering Mapping (ENUM) server for a called party of the session request. The method determines if at least one Naming Authority Pointer (NAPTR) resource record associated with the called party is received from the ENUM server, and forwards the session request to a circuit switched network if the at least one NAPTR resource record is not received from the ENUM server. The method determines a Session Description Protocol (SDP) value of the session request if the at least one NAPTR resource record is received from the ENUM server, and processes the session request in accordance with the SDP value if the at least one NAPTR resource record is received from the ENUM server.

This application is a continuation of U.S. patent application Ser. No.12/334,041, filed Dec. 12, 2008, which is currently allowed and isherein incorporated by reference in its entirety.

The present invention relates generally to communication networks and,more particularly, to a method and apparatus for completing a circuitswitched service call in an Internet Protocol (IP) network, e.g., anInternet Protocol (IP) multimedia subsystem network, a Voice overInternet Protocol (VoIP) network, a Service over Internet Protocol(SoIP) network, and the like.

BACKGROUND OF THE INVENTION

A customer may initiate a voice or data call session over an IPMultimedia Subsystem (IMS) network. The IMS network may then receive andattempt to route the call towards its destination. In order to performthe routing, the network needs to identify a route for the call. Theroute may be determined based on the domain serving the called party.For example, the IMS network may first make a determination of whetheror not a route to the called party is found over the IMS network. If aroute is found over the IMS network, then the call is routed over theIMS network. If no route is found over the IMS network, then the callmay then be forwarded to a circuit switched network through one or morecircuit switched gateway devices, e.g., a border gateway controlfunction, a media gateway control function, and the like.

However, more and more customers are subscribing to multiple services,where some services are provided over an IMS network and others areprovided over non-IMS networks. For example, a customer may subscribe toa video share service provided over an IMS network and the customer mayalso subscribe to a voice service provided over a Global System forMobile (GSM) communications network. Hence, when a call destined towardsa customer who subscribes to both IMS and non-IMS network based servicesis received, an attempt to locate a route to the called party over theIMS network may still be performed even if the call cannot besuccessfully completed over the IMS network.

SUMMARY OF THE INVENTION

In one embodiment, the present invention discloses a method and anapparatus for processing a session request in an IP network. Forexample, the method receives a session request, and queries an tElephoneNUmbering Mapping (ENUM) server for a called party of the sessionrequest. The method determines if at least one Naming Authority Pointer(NAPTR) resource record associated with the called party is receivedfrom the ENUM server, and forwards the session request to a circuitswitched network if the at least one NAPTR resource record is notreceived from the ENUM server. The method determines a SessionDescription Protocol (SDP) value of the session request if the at leastone NAPTR resource record is received from the ENUM server, andprocesses the session request in accordance with the SDP value if the atleast one NAPTR resource record is received from the ENUM server.

BRIEF DESCRIPTION OF THE DRAWINGS

The teaching of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates an exemplary network related to the presentinvention;

FIG. 2 illustrates an exemplary network in accordance with oneembodiment of the current invention for completing a circuit switchedservice call in an IMS network;

FIG. 3 illustrates a flowchart of a method for completing a circuitswitched service call in an IMS network; and

FIG. 4 illustrates a high-level block diagram of a general-purposecomputer suitable for use in performing the functions described herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION

The present invention broadly discloses a method and apparatus forcompleting a circuit switched service call in a network. Although thepresent invention is discussed below in the context of an IP network,e.g., an Internet Protocol (IP) Multimedia Subsystem (IMS) networks, thepresent invention is not so limited. Namely, the present invention canbe applied to packet networks in general, e.g., Voice over InternetProtocol (VoIP) networks, Service over Internet Protocol (SoIP)networks, and the like.

To better understand the present invention, FIG. 1 illustrates anexample network 100, e.g., an Internet Protocol (IP) MultimediaSubsystem network related to the present invention. An IP network isbroadly defined as a network that uses Internet Protocol to exchangedata packets. Exemplary IP Multimedia Subsystem (IMS) networks includeInternet protocol (IP) networks such as Voice over Internet Protocol(VoIP) networks, Service over Internet Protocol (SoIP) networks, and thelike.

In one embodiment, the network 100 may comprise a plurality of endpointdevices 102-104 configured for communication with the core IMS network110 (e.g., an IP based core backbone network supported by a serviceprovider) via an access network 101. Similarly, a plurality of endpointdevices 105-107 are configured for communication with the IMS corepacket network 110 via an access network 108. The network elements 109and 111 may serve as gateway servers or edge routers for the network110.

The endpoint devices 102-107 may comprise customer endpoint devices suchas personal computers, laptop computers, Personal Digital Assistants(PDAs), and the like. The access networks 101 and 108 serve as a meansto establish a connection between the endpoint devices 102-107 and theNetwork Elements (NEs) 109 and 111 of the IMS core network 110. Theaccess networks 101 and 108 may each comprise a Digital Subscriber Line(DSL) network, a broadband cable access network, a Local Area Network(LAN), a Wireless Access Network (WAN), a 3^(rd) party network, and thelike. The access networks 101 and 108 may be either directly connectedto NEs 109 and 111 of the IMS core network 110, or indirectly throughanother network.

Some NEs (e.g., NEs 109 and 111) reside at the edge of the IMS coreinfrastructure and interface with customer endpoints over various typesof access networks. An NE that resides at the edge of a coreinfrastructure is typically implemented as an edge router, a mediagateway, a proxy server, a border element, a firewall, a switch, and thelike. An NE may also reside within the network (e.g., NEs 118-120) andmay be used as a SIP server, a core router, or like device.

The IMS core network 110 also comprises a Home Subscriber Server (HSS)127, a Serving-Call Session Control Function (S-CSCF) 121, a MediaServer (MS) 125, and an Application Server 112 that contains a database115. An HSS 127 refers to a network element residing in the controlplane of the IMS network that acts as a central repository of allcustomer specific authorizations, service profiles, preferences, etc.

The S-CSCF 121 resides within the IMS core infrastructure and isconnected to various network elements (e.g., NEs 109 and 111) using theSession Initiation Protocol (SIP) over the underlying IMS based corebackbone network 110. The S-CSCF 121 may be implemented to registerusers and to provide various services (e.g., VoIP services). The S-CSCFinteracts with the appropriate VoIP/SoIP service related applicationsservers (e.g., application server 112), when necessary. The S-CSCF 121performs routing and maintains session timers. The S-CSCF may alsointerrogate an HSS to retrieve authorization, service information, userprofiles, etc. In order to complete a call that requires certain servicespecific features, the S-CSCF may need to interact with variousapplication servers (e.g., various VoIP servers). For example, theS-CSCF may need to interact with another server for translation of anE.164 voice network address into an IP address, and so on.

The Media Server (MS) 125 is a special server that typically handles andterminates media streams to provide services such as announcements,bridges, and Interactive Voice Response (IVR) messages for VoIP serviceapplications. The media server also interacts with customers for mediasession management to accomplish tasks such as process requests.

The application server 112 may comprise any server or computer that iswell known in the art, and the database 115 may be any type ofelectronic collection of data that is also well known in the art. Thoseskilled in the art will realize that the communication system 100 may beexpanded by including additional endpoint devices, access networks,network elements, application servers, etc. without altering the scopeof the present invention.

The above IP network is described to provide an illustrative environmentin which packets for voice, data and multimedia services are transmittedon IP Multimedia Subsystem (IMS) networks. For example, a customer of anIMS network may initiate a voice or data call. The S-CSCF located in theIMS network may then receive the call and search for a route towards thecalled party over the IMS network. The route for the call may bedetermined based on the domain serving the called party.

For example, the S-CSCF may query an ENUM (tElephone NUmbering Mapping)server (described below) to determine routing information (e.g., homedomain and how calls are to be routed) for the called party. That is,the S-CSCF in the IMS network makes a determination of whether or not aroute to the called party over the IMS network exists. If a route isfound over the IMS network, the call may then be routed over the IMSnetwork. If no route towards the called party is found over the IMSnetwork, then the IMS network may then forward the call towards acircuit switched network through one or more circuit switched gatewaydevices, e.g., a border gateway control function, media gateway controlfunction, and the like. For example, if the called party subscribes onlyto a service from a Public Switched Telephone Network (PSTN), the IMSnetwork will forward received calls to the PSTN via the border gatewaycontrol function and/or media gateway control function.

However, the called party may subscribe to multiple services with atleast one of the services provided over the IMS network. For example,the called party may be a subscriber of a video share service providedover an IMS network, and also may be a subscriber of a voice serviceprovided over a Global System for Mobile (GSM) network. Hence, a routeto the called party over the IMS network may be found, even if the callis a voice call that cannot be successfully routed over the IMS network.That is, the ENUM server may provide a route, even if using theretrieved route results in the voice call being unsuccessful.

In one embodiment, the current method provides a method for completing acircuit switched service call over an IMS network. In order to moreclearly describe the current invention, the following networkingterminologies are first provided.

-   -   E.164; and    -   ENUM (tElephone NUmbering Mapping).

E.164 refers to an ITU (International Telecommunications Union)-Trecommendation which defines the international public telecommunicationnumbering plan for formatting telephone numbers such that they may besignaled across one or more networks. The E.164 format includes acountry code and subsequent digits, but not the international prefix.

ENUM refers to a standard protocol defined by the Internet EngineeringTask Force (IETF) for translating phone numbers that are in E.164 formatto Internet domain names such that a Domain Name Server (DNS) mayresolve the IP addresses for E.164 numbers the same way it resolvestraditional website domains. For example, ENUM may be used to transforma phone, a fax or a pager number into a URI (Uniform ResourceIdentifier).

In order to translate a phone number to an Internet Domain name, thephone number is first provided in an E.164 format. Specifically, thephone number is first translated or converted to a full E.164 formattednumber. For example, the original phone number may not have indicated acountry code, area code, etc. However, an E.164 formatted phone numberincludes a country code, area code and the specific number within thearea code. For example, “1” is the country code for all phone numbers inthe United States of America (USA). If the original USA phone number is987-555-1234, it is translated to an E.164 formatted number yielding1-987-555-1234. The E.164 number is then reduced to digits only, e.g.,19875551234. The digits are then reordered back to front, e.g.43215557891. Once the digits are reordered, dots are placed between eachdigit and the Internet domain e164.arpa is added to the end. For theabove example, the resulting Internet domain is4.3.2.1.5.5.5.7.8.9.1.e164.arpa.

An ENUM server may then be queried by the S-CSCF of the calling party toresolve on the domain name 4.3.2.1.5.5.5.7.8.9.1.e164.arpa. For example,an IP Multimedia Subsystem (IMS) network may use an ENUM server toresolve phone number that is in E.164 format, i.e., the contactinformation of the phone number. The S-CSCF of the calling party maythen query a DNS for the regular routing of the contact informationresided in the NAPTR (Naming Authority Pointer) resource records, e.g.,the SIP URI. In sum, the S-CSCF of the calling party will send the ENUMquery and the ENUM server will return the NAPTR resource records if theE.164 number is registered, wherein the S-CSCF then queries the DNS forthe destination of the returned records, e.g., the SIP URI of the calledparty.

It should be noted that the customer may have a set of NAPTR resourcerecords. For example, the customer may have a SIP address, a telephonenumber, a presence service number, an email address, etc. The query maythen retrieve the set of NAPTR resource records for the customer. Table1 below provides an illustrative example of a query and a response forthe above phone number.

TABLE 1 Query ORIGIN 4.3.2.1.5.5.5.7.8.9.1.e164.arpa Response IN NAPTR100 10 “u” “E2U+SIP” Active “!{circumflex over( )}.*$!sip:user@example.com!” IN NAPTR 100 20 “u” “E2U+pres” Active“!{circumflex over ( )}.*$!pres:user@example.com!” IN NAPTR 100 30 “u”“E2U+mailto” Inactive “!{circumflex over( )}.*$!mailto:user@example.com!”

It should be noted that Table 1 above illustrates a response having aplurality of NAPTR resource records. In this illustrative example, eachNAPTR resource record contains information pertaining to an order (e.g.,represented by the value “100”) followed by a preference (e.g.,represented by the values “10”, “20”, and “30”). In one embodiment, theNAPTR resource records are organized based on the order field and thepreference field, e.g., from a lowest order value to a highest ordervalue and from a lowest preference value to a highest preference value.For example, in operation, the lowest value (e.g., “10” in this example)in the preference field will be executed first and then followed by thenext lowest preference field (e.g., “20” in this example), and so on.This approach allows a call to be directed to a plurality of possibledestinations based upon a preferred order or sequence that can beselectively set by the user.

Furthermore, in one embodiment, each NAPTR resource record may also havean activation field that indicates whether a NAPTR resource record is“active” or “inactive.” An “active” field indicates that the NAPTRresource record can be used, whereas an “inactive” field indicates thatthe NAPTR resource record should not be used. Again, this approachallows a user to selectively activate or deactivate a NAPTR resourcerecord. For example, a user may be travelling on a business trip for anextended period of time and does not want calls directed to the user'shome number while the user is travelling. As such, the user canselectively designate a NAPTR resource record associated with the user'shome number to be “inactive”, during the business trip. Upon return fromthe business trip, the user can selectively designate the NAPTR resourcerecord associated with the user's home number to be “active” again.

If the S-CSCF of the calling party fails to receive a successful NAPTRresource record as a response to the query (queries) sent to the ENUMand DNS, the S-CSCF either rejects the call or assumes that the calledparty is a customer of a Public Switched Telephone Network (PSTN). Ifthe S-CSCF assumes that the called party is a customer of a PSTN, theS-CSCF of the calling party forwards the call to the PSTN network via aBorder Gateway Control Function (BGCF) and/or Media Gateway ControlFunction (MGCF). If the called party is indeed a customer of the PSTN,then the call may successfully complete over the PSTN.

If the S-CSCF of the calling party receives a NAPTR resource record inresponse to the query (queries) sent to the ENUM and DNS, the S-CSCFthen routes the call to the Interrogating-Call Session Control Function(I-CSCF) of the returned domain for termination. That is, the S-CSCFroutes the call to the I-CSCF handling the destination of the returnedrecord. The I-CSCF may then interrogate the HSS to determine the S-CSCFof the called party. If the HSS then returns a Serving-Call SessionControl Function Fully Qualified Domain Name (S-CSCF FDQN) of the calledparty to the I-CSCF, the I-CSCF routes the incoming session request(e.g., SIP INVITE message for the call) to the S-CSCF of the calledparty, in accordance with the received S-CSCF FDQN. The S-CSCF of thecalled party (e.g., termination S-CSCF) forwards the call towards thecalled party via an access Session Border Controller (SBC). The accessSBC is used to facilitate interconnection between access and corenetworks. The access SBC performs routing of the call towards a UserEndpoint (UE) device.

In the example above, the called party may be a subscriber of both IMSbased and non-IMS based services. Consequently, a NAPTR resource recordwould be located by the ENUM server regardless of the type of service(i.e., for both IMS and non-IMS based services). Hence, the access SBCmay receive calls directed to the customer, even if the call may be fora circuit switched service. The access SBC assumes that the call (e.g.,a SIP INVITE) it received is an IP call, and forwards the call towardsthe UE. If the call is for a circuit switched service (e.g., a voicecall to be routed over GSM), the UE is reachable only via the circuitswitched network. For the example above, the voice call wouldsuccessfully complete only if routed to the UE via a circuit switchedgateway and the GSM network. Hence, the voice call routed via the accessSBC will fail to complete.

In one embodiment, the current method provides circuit switched servicecall completion in an IP network, e.g., an IMS network. The method firstenables subscribers of services to register their UE devices in a commonENUM server. For example, the method may enable subscribers of videoshare services to register their UE devices in a common ENUM server. Inone embodiment, the registration includes an indication of whether ornot the UE is capable of receiving, audio, video, etc. For example, ifthe indication for a UE is “E2U+SIP”, then the UE is capable ofreceiving video.

When a call is received, the S-CSCF may determine a type of service forthe call. In one embodiment, the S-CSCF determines the type of servicefrom the value of a Session Description Protocol (SDP) in the sessionrequest. For example, the SIP INVITE (if SIP is used) would include anSDP value. The S-CSCF may then process the SDP value to determine thetype of desired service. If the SDP value is associated with a serviceprovided over the IMS network, the method may then forward the call(e.g., the session request) towards the UE via the S-CSCF of the calledparty and the access SBC. If the SDP value is associated with a serviceprovided over the circuit switched network, the S-CSCF may then forwardthe call towards the circuit switched gateway.

For example, the S-CSCF of the IMS network may receive a voice calldirected towards a customer who subscribes to a voice service over GSMand a video share service over the IMS network. The UE device is thenregistered in a common ENUM server for the video service. The S-CSCF ofthe IMS network may then process calls by first processing the SDPincluded in the call request. If the call is for a video share service,then the S-CSCF of the calling party may then forward the call towardsthe UE using the SIP URI. If the call is for a voice service (e.g.,GSM), the S-CSCF then determines that the telephone URI is to be used.The S-CSCF then forwards the voice call to the GSM network through theBGCF, MGCF and circuit switched gateway device.

FIG. 2 illustrates an exemplary network 200 in accordance with oneembodiment of the current invention for completing a circuit switchedservice call in an IMS network. In one embodiment, the network 200comprises User Endpoint (UE) devices 102 and 105 communicating with anIMS network 110 via access networks 101 and 108, respectively.

In one embodiment, the IMS network 110 comprises P-CSCFs 209 and 211,S-CSCFs 221 and 222, I-CSCFs 230 and 231, HSSs 127 and 128, a commonENUM server 228, a DNS 229, BGCF 240, MGCF 241, a circuit switchedgateway device 234, and access Session Border Controllers (SBCs) 207 and233. In order to provide services to customers, the IMS core network 110is interconnected with the GSM network 242 and the access network 108via the circuit switched gateway device 234 and the access SBC 233,respectively. In one example, the customer using UE device 102 isaccessing services in the IMS network 110 through access Session BorderController 207, P-CSCF 209, S-CSCF 221 and I-CSCF 230. Similarly, thecustomer using UE device 105 is accessing services in the IMS network110 through P-CSCF 211, S-CSCF 222 and I-CSCF 231. The BGCF 240, MGCF241 and circuit switched gateway 234 are used to route calls from theIMS core network 110 to circuit switched networks, e.g., GSM network242.

In one embodiment, the current method enables a customer to registerhis/her UE device in the common ENUM server 228. For example, thecustomer with UE device 105 may subscribe to a video share service andprovide information such that the ENUM server is aware of thecapabilities of the UE 105. For example, the customer may indicate thatthe UE 105 is SIP capable (e.g., for supporting video share).

In one embodiment, if UE 102 initiates a session towards UE 105 (e.g., aSIP INVITE message), the S-CSCF 221 receives the session request viaP-CSCF 209. The S-CSCF 221 may then query for NAPTR resource records tothe common ENUM server 228. The common ENUM server 228 may then returnthe NAPTR resource records (if any). Since UE 105 is registered, a NAPTRresource record will be found. The S-CSCF 221 may then query the DNS 229for the destination of the returned NAPTR records, e.g., the SIP URI andthe telephone URI of the called party. The method also determines andstores the value in the Service Description Protocol (SDP) of thesession request in advance.

In one embodiment, if the SDP is for a service provided over a circuitswitched network, the S-CSCF may then send the session request using thetelephone URI. For the example above, since the customer receives voicecalls over the GSM network 242, the S-CSCF 221 forwards the sessionrequest to the GSM network via the BGCF 240, MGCF 241 and the circuitswitched gateway 234.

In one embodiment, if the SDP is for a service provided over the IMSnetwork (e.g., video share), the S-CSCF may then send the sessionrequest using the SIP URI. For example, since the customer receivesvideo share over the access network 108, the S-CSCF 221 forwards thesession request to the I-CSCF 231. The I-CSCF 231 may then query the HSS128 for the S-CSCF serving the domain of UE 105. HSS 128 may thenprovide a response to the I-CSCF 231 identifying S-CSCF 222 as theserving CSCF for the domain of UE 105. The I-CSCF 231 may then forwardthe session request to S-CSCF 222. The S-CSCF 222 may then forward thesession request to the access SBC 233 for completion. The call may thenbe forwarded to UE 105 via the access SBC 233 and access network 108.

FIG. 3 illustrates a flowchart of a method 300 for an S-CSCF forcompleting a circuit switched service call in an IMS network. Forexample, one or more steps of the step 300 can be implemented in anS-CSCF serving a calling party in an IP network, e.g., an IMS network.Method 300 starts in step 305 and proceeds to step 310.

In step 310, method 300 receives a session request. For example, anS-CSCF may receive a SIP INVITE message from a subscriber of a VoIPservice through a proxy-CSCF.

In Step 312, method 300 determines a Session Description Protocol (SDP)value of the session request and stores it for later processing. Forexample, the method as discussed below may process the session requestto determine if the service in the session request is provided using atelephone URI or a SIP URI. For example, if the value of the SDP in thesession request is that of a video share service, then the service isprovided over a SIP URI.

In step 315, method 300 queries an ENUM server for a called party of thesession request. For example, the method may query the ENUM server forone or more NAPTR records associated with the called party in thesession request. If a NAPTR record is found, then the NAPTR record maybe used to query a DNS for the destination of the returned NAPTR record,e.g., the SIP URI or telephone URI associated with a called party may beretrieved from a DNS.

In step 320, method 300 determines if at least one NAPTR resource recordis received from the ENUM server. If at least one NAPTR resource recordis received from the ENUM server, then the method proceeds to step 325.Otherwise, the method proceeds to step 370.

In step 325. Method 300 retrieves the stored value of the SessionDescription Protocol (SDP) and determines how to process the servicerequest.

In step 330, method 300 determines if the SDP value of the sessionrequest is for a service provided over the IMS network. If the SDP isfor a service provided over the IMS network, then the method proceeds tostep 335. Otherwise, the method proceeds to step 350.

In step 335, method 300 processes the session request in accordance withthe SDP. For example, the method may forward the session request towardsthe called party over the IMS network using a SIP URI. For example, ifthe SDP is for a service provided over the IMS network (e.g., a videoshare service), the S-CSCF may then send the session request towards thedestination address using the SIP URI. Specifically, the session requestmay be forwarded to the I-CSCF of the domain of the IMS. The I-CSCF maythen query the HSS for the S-CSCF serving the called party. The HSS maythen provide a response to the I-CSCF identifying the S-CSCF that servesthe domain of the called party. The I-CSCF may then forward the sessionrequest to the S-CSCF of the called party. The S-CSCF of the calledparty may then forward the session request to the access SBC, which thenforwards the session request to the called party. The method then endsin step 390 or returns to step 310 to continue receiving more requests.

In step 350, method 300 forwards the session request to a circuitswitched network using a telephone URI. For example, the S-CSCF may sendthe session request to a GSM or PSTN using the telephone URI. Thesession request may then reach the GSM or PSTN via a BGCF, an MGCF and acircuit switched network gateway device. The method then ends in step390 or returns to step 310 to continue receiving more requests.

In step 370, method 300 forwards the session request to a circuitswitched network. For example, the method may forward the sessionrequest to a GSM or PSTN for completion, via a circuit switched networkgateway device. The method then ends in step 390 or returns to step 310to continue receiving more requests.

It should be noted that although not specifically specified, one or moresteps of method 300 may include a storing, displaying and/or outputtingstep as required for a particular application. In other words, any data,records, fields, and/or intermediate results discussed in the method canbe stored, displayed and/or outputted to another device as required fora particular application. Furthermore, steps or blocks in FIG. 3 thatrecite a determining operation or involve a decision, do not necessarilyrequire that both branches of the determining operation be practiced. Inother words, one of the branches of the determining operation can bedeemed as an optional step.

FIG. 4 depicts a high-level block diagram of a general-purpose computersuitable for use in performing the functions described herein. Asdepicted in FIG. 4, the system 400 comprises a processor element 402(e.g., a CPU), a memory 404, e.g., random access memory (RAM) and/orread only memory (ROM), a module 405 for completing a circuit switchedservice call in an IP network, and various input/output devices 406(e.g., storage devices, including but not limited to, a tape drive, afloppy drive, a hard disk drive or a compact disk drive, a receiver, atransmitter, a speaker, a display, a speech synthesizer, an output port,and a user input device (such as a keyboard, a keypad, a mouse, and thelike)).

It should be noted that the present invention can be implemented insoftware and/or in a combination of software and hardware, e.g., usingapplication specific integrated circuits (ASIC), a general purposecomputer or any other hardware equivalents. In one embodiment, thepresent module or process 405 for completing a circuit switched servicecall in an IP network can be loaded into memory 404 and executed byprocessor 402 to implement the functions as discussed above. As such,the present method 405 for completing a circuit switched service call inan IP network (including associated data structures) of the presentinvention can be stored on a computer readable medium, e.g., RAM memory,magnetic or optical drive or diskette and the like.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

What is claimed is:
 1. A method for processing a session request in apacket network, comprising: receiving, by a processor, the sessionrequest; querying, by the processor, a telephone numbering mappingserver for a called party of the session request; determining, by theprocessor, if a naming authority pointer resource record associated withthe called party is received from the telephone numbering mappingserver; forwarding, by the processor, the session request to a circuitswitched network if the naming authority pointer resource record is notreceived from the telephone numbering mapping server; determining, bythe processor, a session description protocol value of the sessionrequest if the naming authority pointer resource record is received fromthe telephone numbering mapping server, wherein the session descriptionprotocol value defines a type of service; and processing, by theprocessor, the session request in accordance with the sessiondescription protocol value if the naming authority pointer resourcerecord is received from the telephone numbering mapping server, whereinthe processing the session request comprises forwarding the sessionrequest towards the called party over the packet network if the sessiondescription protocol value of the session request is for a serviceprovided over the packet network.
 2. The method of claim 1, wherein thesession request is an invite message in accordance with a sessioninitiation protocol.
 3. The method of claim 1, wherein the serviceprovided over the packet network comprises a video share service.
 4. Themethod of claim 1, wherein the forwarding the session request towardsthe called party over the packet network is performed using a sessioninitiation protocol universal resource identifier.
 5. The method ofclaim 1, wherein the circuit switched network comprises a publicswitched telephone network.
 6. The method of claim 1, wherein theforwarding the session request to the circuit switched network isperformed using a telephone universal resource identifier.
 7. The methodof claim 1, wherein the packet network comprises an internet protocolnetwork.
 8. A non-transitory computer-readable medium having storedthereon a plurality of instructions which, when executed by a processor,cause the processor to perform operations for processing a sessionrequest in a packet network, the operations comprising: receiving thesession request; querying a telephone numbering mapping server for acalled party of the session request; determining if a naming authoritypointer resource record associated with the called party is receivedfrom the telephone numbering mapping server; forwarding the sessionrequest to a circuit switched network if the naming authority pointerresource record is not received from the telephone numbering mappingserver; determining a session description protocol value of the sessionrequest if the naming authority pointer resource record is received fromthe telephone numbering mapping server, wherein the session descriptionprotocol value defines a type of service; and processing the sessionrequest in accordance with the session description protocol value if thenaming authority pointer resource record is received from the telephonenumbering mapping server, wherein the processing the session requestcomprises forwarding the session request towards the called party overthe packet network if the session description protocol value of thesession request is for a service provided over the packet network. 9.The non-transitory computer-readable medium of claim 8, wherein thesession request is an invite message in accordance with a sessioninitiation protocol.
 10. The non-transitory computer-readable medium ofclaim 8, wherein the service provided over the internet protocol networkcomprises a video share service.
 11. The non-transitorycomputer-readable medium of claim 8, wherein the forwarding the sessionrequest towards the called party over the internet protocol network isperformed using a session initiation protocol universal resourceidentifier.
 12. The non-transitory computer-readable medium of claim 8,wherein the circuit switched network comprises a public switchedtelephone network.
 13. The non-transitory computer-readable medium ofclaim 8, wherein the forwarding the session request to the circuitswitched network is performed using a telephone universal resourceidentifier.
 14. The non-transitory computer-readable medium of claim 8,wherein the packet network comprises an internet protocol network. 15.An apparatus for processing a session request in an internet protocolnetwork, comprising: a processor; and a computer-readable medium storinga plurality of instructions which, when executed by the processor, causethe processor to perform operations, the operations comprising:receiving the session request; querying a telephone numbering mappingserver for a called party of the session request; determining if anaming authority pointer resource record associated with the calledparty is received from the telephone numbering mapping server;forwarding the session request to a circuit switched network if thenaming authority pointer resource record is not received from thetelephone numbering mapping server; determining a session descriptionprotocol value of the session request if the naming authority pointerresource record is received from the telephone numbering mapping server,wherein the session description protocol value defines a type ofservice; and processing the session request in accordance with thesession description protocol value if the naming authority pointerresource record is received from the telephone numbering mapping server,wherein the processing the session request comprises forwarding thesession request towards the called party over the internet protocolnetwork if the session description protocol value of the session requestis for a service provided over the Internet protocol network.
 16. Theapparatus of claim 15, wherein the session request is an invite messagein accordance with a session initiation protocol.
 17. The apparatus ofclaim 15, wherein the service provided over the internet protocolnetwork comprises a video share service.
 18. The apparatus of claim 15,wherein the forwarding the session request towards the called party overthe internet protocol network is performed using a session initiationprotocol universal resource identifier.
 19. The apparatus of claim 15,wherein the circuit switched network comprises a public switchedtelephone network.
 20. The apparatus of claim 15, wherein the forwardingthe session request to the circuit switched network is performed using atelephone universal resource identifier.